Abstract:
A device includes a controller that receives current values generated by at least four parallel load commutated inverters (LCIs). The controller includes a source firing generator that generates independent source firing commands for each of the at least four parallel LCIs based on the received current values and transmits each of the independent source firing commands to a respective one of the at least four parallel LCIs, wherein the source firing commands are configured to set input phase angle values of the four parallel LCIs.
Abstract:
An apparatus includes a DC-link, a voltage converter, a bus voltage controller, and a supervisory controller. The voltage converter is configured to convert a first DC voltage into a second DC voltage based on a command signal and based on an adjustment signal and to supply the second DC voltage to the DC-link. The bus voltage controller is configured to iterate calculation of the adjustment signal to communicate each iterated calculation of the adjustment signal to the voltage converter. The supervisory controller is configured to iterate calculation of the command signal and to communicate each iterated calculation of the command signal to the voltage converter and to the bus voltage controller. A frequency of the bus voltage controller to communicate each iterated calculation of the adjustment signal is higher than a frequency of the supervisory controller to communicate each iterated calculation of the command signal.
Abstract:
Switching control systems and methods are presented for controlling power conversion systems to provide electrical power to a grid or other load in which a synchronous machine is driven by a wind turbine or other prime mover to provide generator power to a switching type current source converter (CSC), with a current source rectifier (CSR) of the CSC being switched to provide d-axis control of the synchronous machine current based on grid power factor feedback, and with a current source inverter (CSI) of the CSC being switched to provide leading firing angle control and selective employment of dumping resists to dissipate excess generator energy in a fault mode when a grid voltage drops below a predetermined level.
Abstract:
An apparatus includes a DC-link, a voltage converter, a bus voltage controller, and a supervisory controller. The voltage converter is configured to convert a first DC voltage into a second DC voltage based on a command signal and based on an adjustment signal and to supply the second DC voltage to the DC-link. The bus voltage controller is configured to iterate calculation of the adjustment signal to communicate each iterated calculation of the adjustment signal to the voltage converter. The supervisory controller is configured to iterate calculation of the command signal and to communicate each iterated calculation of the command signal to the voltage converter and to the bus voltage controller. A frequency of the bus voltage controller to communicate each iterated calculation of the adjustment signal is higher than a frequency of the supervisory controller to communicate each iterated calculation of the command signal.
Abstract:
A system for controlling the operation of an alternating current induction motor having windings supplied by electrical power from the polyphase alternating current source includes a load commutated inverter circuit which is connected between the power source and the induction motor for furnishing electrical power to the motor. Controllers responsive to a command signal and a feedback signal indicative of motor operating parameters control the operation of said load commutated inverter circuit. There is further provided a fixed capacitor circuit connected between the windings of the motor for supplying reactive volt ampheres (VARs) to said load commutated inverter circuit and said motor. Finally, there is provided a variable VAR generator connected between the motor windings for supplying VARs to said load commutated inverter circuit and said motor in response to the output of a third feedback control path which is also responsive to a command signal and prescribed operating parameter(s) of said load and/or said commutated inverter.
Abstract:
A circuit for energizing and controlling a synchronous rotary machine which operates at variable speed and is fed by controlled static switches, wherein the stator of the rotating machine has a plurality n of polyphase windings where n is at least equal to two, each polyphase winding being fed by a static AC-AC converter (A, B) which constitutes an autosychronous inverter having a mains bridge (PRA, PRB) and a machine bridge (PMA, PMB) connected to each other by first and second DC conductors, and wherein the circuit has means for controlling the mains bridge of each converter in such a way that the sum of the DC currents (IA+IB) in said conductors of all the converters is proportional to a reference average current value.
Abstract:
A load commutated inverter synchronous motor drive system wherein a thyristor firing control of the inverter is determined by the amplitude of pesudo flux waveforms which are derived from the integral of the line voltages coupling the inverter to the motor being driven. A firing strategy is provided based on the premise that optimum thyristor firing in a load commutated inverter operating at a leading power factor occurs at a point just below the peak of the forthcoming pseudo flux waveform which point comprises an amount of volt-seconds necessary to effect current commutation plus a nominal safety margin. The determination and control is implemented, preferably, in a software phase lock loop but can, when desirable, be implemented in hardware.
Abstract:
A first static commutator including a first controllable thyristor rectifier and a first thyristor inverter and a second static commutator including a second controllable thyristor rectifier and a second thyristor inverter are provided. First three-phase AC voltage is supplied to the first controllable rectifier, and second three-phase AC voltage 30 degrees out of phase with said first three-phase AC voltage is supplied to the second controllable rectifier. A brushless motor includes first star-connected three-phase windings receiving the output of the first inverter and second star-connected three-phase windings and 30 degrees out of phase with said first three phase windings. During the starting period of the brushless motor the conduction of the first and second satic commutators is switched for every 30-degree rotation of the brushless motor.
Abstract:
A slip-recovery AC motor drive includes two inverters connected in series between the DC link terminals derived from the rectifier coupled with the rotor, and the thyristors are controlled asymmetrically between pairs of half-bridges pertaining to different inverters, thereby to by-pass the output of one inverter alternately during successive equal time intervals of conduction. The recovery transformer has two secondaries each connected to a corresponding inverter output.
Abstract:
A motor drive apparatus has G groups (G.gtoreq.2) of m-phases inverter units and G groups (G.gtoreq.2) of m-phases AC windings for feeding through the m-phases inverter units to the m-phases AC windings and G groups (G.gtoreq.2) of DC power sources which are connected to G groups of the inverter units so as to form alternative series closed loops on the DC circuit.